TW202140993A - Film thickness measuring device and film thickness measuring method - Google Patents

Abstract

This film thickness measuring device comprises: a light radiation part that radiates light onto a target in a planar manner; an optical element, for which the transmittance and reflectance change according to wavelength in a specified wavelength range, which separates light coming from the target via transmitting and reflecting said light; an imaging part which images the light separated by the optical element; and an analysis part which estimates the film thickness of the target on the basis of a signal from the imaging part that has imaged the light. The light radiation part radiates light of a wavelength contained in the specified wavelength range of the optical element.

Description

Film thickness measuring device and film thickness measuring method

One aspect of the present invention relates to a film thickness measuring device and a film thickness measuring method.

For example, in semiconductor manufacturing equipment, it is important to uniformly form a film on the wafer surface. When the in-plane uniformity of the film thickness value is poor, fault factors such as poor wiring or voids occur, and the yield deteriorates. In this case, due to the increase in process time and materials, deterioration of production efficiency becomes a problem. Therefore, in semiconductor manufacturing equipment and the like, usually, the film thickness is measured by a point sensor or a line scan (for example, refer to Patent Document 1), and it is determined whether or not it has a desired film thickness distribution. [Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Application Publication No. 2018-205132

[The problem to be solved by the invention]

Here, in the above-mentioned method of measuring the film thickness by a point sensor or a line scan, a long measurement time becomes a problem.

One aspect of the present invention was completed in view of the above-mentioned actual situation, and its object is to provide a film thickness measuring device and a film thickness measuring method capable of measuring film thickness at high speed. [Technical means to solve the problem]

A film thickness measuring device of one aspect of the present invention includes: a light irradiating section that irradiates light in a planar manner to an object; an optical element in which the transmittance and reflectance change in accordance with the wavelength in a specific wavelength band. The light from the object is separated by transmission and reflection; the imaging section, which captures the light separated by the optical element; and the analysis section, which estimates the film thickness of the object based on the signal from the imaging section that captured the light; And the light irradiating part irradiates the light of the wavelength contained in the specific wavelength band of the optical element.

In the film thickness measuring device of one aspect of the present invention, the object is irradiated with light of the wavelength contained in the specific wavelength band of the optical element in a planar manner. Furthermore, in this film thickness measuring device, the optical element separates the light from the object by transmitting and reflecting. Here, the transmittance and reflectance of the optical element in a specific wavelength band change in accordance with the wavelength. Therefore, the transmitted ratio and the reflected ratio of the separated light in the optical element change according to the wavelength. Furthermore, by capturing the separated light in the imaging unit, the ratio of the transmitted light and the ratio of the reflected light can be specified, and as a result, the wavelength can be specified. Furthermore, in the analysis unit, the film thickness of the object is estimated based on the signal from the imaging unit. In the case that the film thickness can be estimated based on the information indicating the wavelength, as described above, the wavelength is specified based on the imaging result of the imaging unit, so by considering the signal containing the information of the wavelength (the signal from the imaging unit), it can be higher Precisely estimate the film thickness of the object. Moreover, in this film thickness measuring device, the target is irradiated with light in a planar manner, and the film thickness in the surface of the target is estimated corresponding to the light from the target, so it is combined with a point sensor or Line scan, etc., change the range of light irradiation, and estimate the film thickness in the plane at a high speed. As described above, according to the film thickness measuring device of one aspect of the present invention, the film thickness of an object can be measured at a high speed.

In the above-mentioned film thickness measuring device, the analysis unit can estimate the film thickness corresponding to each pixel based on the wavelength information of each pixel of the imaging unit. According to such a configuration, the film thickness distribution of the illuminated surface of the object can be estimated in more detail (for each pixel).

In the above-mentioned film thickness measuring device, the analysis unit may further consider the angle of the light irradiated on the object to estimate the film thickness. If the angle of the light irradiated on the object changes, the optical path changes. Therefore, there are cases in which the film thickness cannot be estimated with high accuracy based on only the wavelength information. At this point, by further considering the angle of the light irradiated on the object, the film thickness can be estimated with higher accuracy corresponding to the actual light path.

In the above-mentioned film thickness measuring device, the light irradiation unit may irradiate the object with diffused light. With this, the surface of the object can be irradiated with light uniformly.

In the above-mentioned film thickness measuring device, the light irradiation section may have a light guide plate that generates diffused light. With this, it is possible to have a compact structure and uniformly irradiate the surface of the object with light.

The above-mentioned film thickness measuring device may further include a band-pass filter arranged between the optical element and the imaging unit. Thereby, light outside the desired wavelength range can be removed, and the accuracy of film thickness estimation can be improved.

The film thickness measurement method of one aspect of the present invention includes: a first step of irradiating light in a plane to an object; a second step of photographing light separated by an optical element that is in a specific wavelength band , The transmittance and reflectance change in accordance with the wavelength, and the light from the object is separated by transmission and reflection; and the third step is to derive the wavelength based on the imaging result, and estimate the film thickness of the object based on the wavelength . According to such a film thickness measurement method, the film thickness of an object can be measured at a high speed in the same way as the above-mentioned film thickness measurement device. [Effects of the invention]

According to the film thickness measuring device of one aspect of the present invention, the film thickness of the object can be measured at high speed.

Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same symbol is assigned to the same or corresponding part, and the repeated description is abbreviate|omitted.

Fig. 1 is a diagram schematically showing the film thickness measuring device 1 of the present embodiment. The film thickness measuring device 1 is a device that irradiates a sample 100 (object) with light in a planar manner, and measures the thickness of a film formed on the sample 100 based on the reflected light from the sample 100. The sample 100 can be a light-emitting device such as LED, micro LED, μLED, SLD device, laser device, vertical laser device (VCSEL), OLED, etc., and it can also be adjusted by fluorescent materials including nanodots. Light-emitting element with light-emitting wavelength.

As shown in FIG. 1, the film thickness measurement apparatus 1 is equipped with the light source 10 (light irradiation part), the camera system 20, and the control device 30 (analysis part).

The light source 10 irradiates the sample 100 with light in a planar shape. For example, the light source 10 irradiates light in a planar manner to substantially the entire surface of the sample 100. The light source 10 is, for example, a light source that can uniformly irradiate the surface of the sample 100 and irradiate the sample 100 with diffuse light. As shown in FIG. 2, the light source 10 may be a so-called flat dome-type light source 10A (refer to FIG. 2(a)), or a dome-type light source 10B (refer to FIG. 2(b)). The light source 10A shown in FIG. 2(a) has an LED 10c and a light guide plate 10d. The light guide plate 10d generates diffused light corresponding to the light irradiated from the LED 10c. The diffused light generated by the light guide plate 10 d is reflected in the sample 100 and input to the camera system 20. According to such a flat dome-shaped light source 10A, it is possible to ensure a sufficient field of view (for example, a field of view of about 300 mm) while suppressing reflection. The light source 10B has an LED 10e and a dome 10f. The light irradiated from the LED 10e is irradiated toward the inner surface of the dome 10f, the diffused light from the inner surface of the dome 10f is reflected in the sample 100, and the reflected light of the sample 100 is input to the camera system 20. The light source 10 can be a surface lighting unit using white LEDs, halogen lamps, or Xe lamps.

The light source 10 irradiates the sample 100 with light of the wavelength contained in the specific wavelength band of the inclined dichroic mirror 22 (details will be described later) of the camera system 20. Although the details are described later, the inclined dichroic mirror 22 is an optical element that separates the light from the sample 100 by transmitting and reflecting corresponding to the wavelength. In the above-mentioned specific wavelength band of the inclined dichroic mirror 22, the transmittance and reflectance of the inclined dichroic mirror 22 vary in accordance with the wavelength.

FIG. 3 is a diagram illustrating the relationship between the characteristics of the inclined dichroic mirror 22 and the wavelength of the light emitted from the light source 10. In FIG. 3, the horizontal axis represents the wavelength, and the vertical axis represents the transmittance of the inclined dichroic mirror 22. As shown in the characteristic X4 of the inclined dichroic mirror 22 in FIG. 3, in the inclined dichroic mirror 22, in a specific wavelength band X10, the transmittance (and reflectance) of light corresponds to the wavelength The change changes gently. In the wavelength band outside the specific wavelength band, regardless of the change of the wavelength, the light transmittance (and reflectance) is set to be constant. As shown in FIG. 3, the light X20 output from the light source 10 includes the light of the wavelength contained in the above-mentioned specific wavelength band X10. That is, the light source 10 outputs light of a broad spectrum including a specific wavelength band X10. In addition, the measured wavelength band (interference peak wavelength) is determined by the material of the film formed on the sample 100 and the measured film thickness range.

Returning to FIG. 1, the camera system 20 includes a lens 21, a tilt dichroic mirror 22 (optical element), area sensors 23 and 24 (imaging unit), and band-pass filters 25 and 26.

The lens 21 is a lens that collects the incident light from the sample 100. The lens 21 can be arranged in the front section (upstream) of the inclined dichroic mirror 22 or in the area between the inclined dichroic mirror 22 and the area sensors 23 and 24. The lens 21 may be a finite focus lens or an infinite focus lens. In the case where the lens 21 is a finite focus lens, the distance between the lens 21 and the area sensors 23 and 24 is set to a specific value. In the case that the lens 21 is an infinite focus lens, the lens 21 is a collimating lens that converts the light from the sample 100 into parallel light to obtain parallel light for aberration correction. The light output from the lens 21 enters the inclined dichroic mirror 22.

The inclined dichroic mirror 22 is a mirror made of special optical materials, and is an optical element that separates the light from the sample 100 by transmitting and reflecting corresponding to the wavelength. The inclined dichroic mirror 22 is configured to be in a specific wavelength band, and the transmittance and reflectance of light change in accordance with the wavelength.

4 is a diagram illustrating the spectrum of light and the characteristics of the inclined dichroic mirror 22. In FIG. 4, the horizontal axis represents the wavelength, and the vertical axis represents the spectral intensity (in the case of the light spectrum) and transmittance (in the case of the inclined dichroic mirror 22). As shown in the characteristic X4 of the inclined dichroic mirror 22 in FIG. 4, in the inclined dichroic mirror 22, in a specific wavelength band (wavelength band of wavelength λ ₁ to λ ₂ ), the light The transmittance (and reflectance) changes gently in response to the change in wavelength, in a wavelength band outside the specific wavelength band (that is, the wavelength λ ₁ is on the low wavelength side, and the wavelength λ ₂ is on the high wavelength side) , Regardless of the change in wavelength, the transmittance (and reflectance) of the light is set to be constant. In other words, in a specific wavelength band (wavelength band of wavelength λ ₁ to λ ₂ ), the transmittance of light monotonously increases (the reflectance decreases monotonously) in accordance with the change of the wavelength. Since the transmittance and reflectance are negatively correlated if one changes in the direction of increasing, the other changes in the direction of decreasing, so the following is simply described as "transmittance" instead of "transmittance" (And reflectivity)". In addition, "regardless of the change in wavelength, the transmittance of the average light is constant" includes not only the case where the transmittance is completely constant, but also the case where the change in the transmittance with respect to the change in wavelength of 1 nm is 0.1% or less. On the lower wavelength side than the wavelength λ ₁ , the light transmittance is approximately 0% _{regardless of the change in wavelength, and on the higher wavelength side than the wavelength λ 2} , the light transmittance is approximately 100 regardless of the wavelength change %. In addition, "light transmittance roughly 0%" includes a transmittance of about 0%+10%, and "light transmittance roughly 100%" includes a transmittance of about 100%-10%. In FIG. 4, the waveform X1 represents the waveform of the light output from the light source 10. As shown by the waveform X1 in FIG. 4, the light output from the light source 10 includes the light of the wavelength contained in the specific wavelength band of the inclined dichroic mirror 22 (the wavelength band of wavelengths λ ₁ to λ ₂ ).

The area sensors 23 and 24 photograph the light separated by the inclined dichroic mirror 22. The area sensor 23 captures the light transmitted through the inclined dichroic mirror 22. The area sensor 24 captures the light reflected in the inclined dichroic mirror 22. The range of wavelengths in which the area sensors 23 and 24 have sensitivity corresponds to a specific wavelength band in which the transmittance (and reflectance) of the light in the inclined dichroic mirror 22 changes in response to the change in wavelength. The area sensors 23 and 24 are, for example, monochrome sensors or color sensors. The imaging results (images) obtained by the area sensors 23 and 24 are output to the control device 30.

The band pass filter 25 is disposed between the inclined dichroic mirror 22 and the area sensor 23. The band pass filter 26 is disposed between the inclined dichroic mirror 22 and the area sensor 24. The bandpass filters 25, 26 can be, for example, light that removes wavelength bands other than the above-mentioned specific wavelength band (in the inclined dichroic mirror 22, the transmittance and reflectance of the light correspond to the wavelength band of the wavelength change). The filter.

Returning to FIG. 1, the control device 30 is a computer, which is physically configured with RAM, ROM and other memory, CPU and other processors (arithmetic circuits), communication interface, hard disk and other storage units. The control device 30 functions by executing a program stored in the memory with the CPU of the computer system. The control device 30 can be constituted by a microcomputer or an FPGA.

The control device 30 estimates the film thickness of the sample 100 based on the signals from the area sensors 23 and 24 that picked up the light. The control device 30 estimates the film thickness corresponding to each pixel based on the wavelength information of each pixel of the area sensors 23 and 24. In more detail, the control device 30 is based on: the amount of transmitted light specified based on the imaging result of the area sensor 23 (signal from the area sensor 23), and the imaging result based on the area sensor 24 (from the area sensor The signal of the device 24) and the amount of reflected light specified, the center wavelength of the inclined dichroic mirror 22 (the center wavelength of the specified wavelength band), and the width of the inclined dichroic mirror 22 are derived for each pixel The center of gravity of the wavelength of light, and the film thickness corresponding to each pixel is estimated based on the center of gravity of the wavelength. The width of the inclined dichroic mirror 22 is, for example, the wavelength width of the wavelength at which the transmittance becomes 0% in the inclined dichroic mirror 22 to the wavelength at which the transmittance becomes 100%.

Specifically, the control device 30 derives the center of gravity of the wavelength of each pixel based on the following equation (1). In the following formula (1), λ represents the center of gravity of the wavelength, λ ₀ represents the center wavelength of the inclined dichroic mirror 22, A represents the width of the inclined dichroic mirror 22, R represents the amount of reflected light, and T represents the transmission The amount of light. λ=λ ₀ +A(TR)/2(T+R) (1)

Fig. 5 is a diagram illustrating the wavelength shift corresponding to the amount of transmitted light and the amount of reflected light. In the case of deriving λ (wavelength center of gravity) from the above formula (1), as shown in Figure 5, for the pixel of T (transmitted light) = R (reflected light), set λ = λ ₀ (tilt two To the center wavelength of the dichroic mirror 22). In addition, for a pixel with T<R, that is, a pixel in which the amount of reflected light is greater than the amount of transmitted light, λ=λ ₁ (the wavelength on the shorter wavelength side is shorter than λ _0). In addition, for a pixel with T>R, that is, a pixel in which the amount of transmitted light is greater than the amount of reflected light, λ=λ ₂ (the wavelength on the longer wavelength side _{than λ 0).} In this way, the value of λ (wavelength center of gravity) is shifted (wavelength shift) based on the amount of transmitted light and the amount of reflected light.

In addition, the method of deriving the center of gravity of the wavelength is not limited to the above. For example, since λ (wavelength center of gravity) has a proportional relationship with the following x, the wavelength center of gravity can be derived from the following equations (2) and (3). In the following formula (3), I _T represents the amount of transmitted light, and I _R represents the amount of reflected light. In addition, when the spectral shape of the object to be measured and the line of the inclined dichroic mirror 22 are formed into ideal shapes, a and b as the parameters of the formula (2) are determined by the optics of the inclined dichroic mirror 22 Characteristic decision. λ=ax+b (2) x=I _T -I _R /2(I _T +I _R ) (3)

In addition, since there are actually differences (individual differences) in the spectral characteristics between the optical system and the camera, for the purpose of correcting them, for example, the signal intensity of the substrate whose reflection characteristics are known can be used as a reference. The following equation (4) derives x. In the following formula (4), I _Tr represents the amount of reference transmitted light, and I _Rr represents the amount of reference reflected light. x=(I _T /I _Tr -I _R /I _Rr )/2(I _T /I _Tr +I _R /I _Rr ) (4)

In addition, for the purpose of removing the influence of the direct light from the light source, the signal quantity in the non-reflective state can be used to derive x according to the following formula (5). In the following formula (5), I _Tb represents the amount of transmitted light in the _{non-reflective state, and I Rb} represents the amount of reflected light in the non-reflective state. x={(I _T -I _Tb )/(I _Tr -I _Tb )-(I _R -I _Rb )/(I _Rr -I _Rb ))/2{(I _T -I _Tb )/(I _Tr- I _Tb )+(I _R -I _Rb )/(I _Rr -I _Rb )) (5)

In addition, in order to implement various corrections of film characteristics, irradiation spectrum, and non-linearity of the inclined dichroic mirror 22 in general, the wavelength center of gravity (λ) can be approximated by the polynomial of the following equation (6). In addition, each parameter (a, b, c, d, e) of the following formula (6) is determined by, for example, measuring samples with different wavelength centers of gravity (film thickness) a plurality of times. λ=ax ⁴ +bx ³ +cx ² +dx+e (6)

Figure 6 is a diagram illustrating the principle of film thickness measurement. In FIG. 6, the horizontal axis is the wavelength, and the vertical axis is the reflectance. In the example shown in FIG. 6, the relationship between the wavelength and the reflectance is shown for each of the film thicknesses of 820 nm, 830 nm, and 840 nm. As shown in Figure 6, the center of gravity of the wavelength varies with the thickness of the film. Therefore, by specifying the center of gravity of the wavelength, the film thickness can be estimated.

The relationship between wavelength and film thickness can be illustrated by the following equation (7) as shown in FIG. 7. In the following formula (7), n represents the refractive index of the film, and d represents the film thickness. m represents a positive integer (1, 2, 3,...), and λ represents the center of gravity of the wavelength. 2nd represents the optical path difference (the optical path difference caused by the placement of the film). The control device 30 estimates the film thickness corresponding to each pixel from the center of gravity of the wavelength of each pixel based on the following equation (7). 2nd=mλ(m=1, 2, 3,...) (Enhanced condition) 2nd=(m-1/2)λ(m=1, 2, 3,...) (weakening condition)・・(7)

Here, the above-mentioned formula (7) representing the relationship between the wavelength and the film thickness holds true when light enters the sample 100 perpendicularly. On the other hand, in the case where the light is not incident perpendicularly to the sample 100, the above formula (7) does not hold. That is, as shown in FIG. 8, when light is incident on the sample 100 on which the film 101 is arranged on the surface of the substrate 102, since the incident angle of the light differs depending on the measurement point and the optical path difference is different, it cannot be uniformly based on the above The formula (7) estimates the film thickness with high accuracy. Therefore, in order to estimate the film thickness with high accuracy at any measurement point (incident angle), calculation (correction processing) corresponding to the measurement point (incident angle) is necessary.

Fig. 9 is a diagram illustrating the correction of the measured value of the film thickness. As shown in Figure 9(a), when the incident angle of light is θ, the optical path difference is represented by 2ndcosθ. Therefore, the relationship between the wavelength and the film thickness having the incident angle θ considered can be explained by the following equation (8) as shown in FIG. 9(b). The control device 30 estimates the film thickness corresponding to the measurement point (incident angle) based on the following equation (8). In this way, the control device 30 can further consider the angle of the light irradiated on the sample 100, and estimate the film thickness based on the center of gravity of the wavelength. 2ndcosθ=mλ (Enhanced condition) 2ndcosθ=(m-1/2)λ (weakening condition)・・(8)

As described above, the film thickness measurement device 1 implements the film thickness measurement method. The film thickness measurement method includes, for example, the first step of irradiating the sample 100 with light in a planar manner; the second step of photographing the light separated by the inclined dichroic mirror 22, the inclined dichroic mirror 22 In a specific wavelength band, the transmittance and reflectance corresponding to the wavelength change, the light from the sample 100 is separated by transmission and reflection; and the third step is to derive the wavelength based on the imaging result, and based on the wavelength , Estimate the film thickness of sample 100.

Next, the effect of this embodiment will be explained.

The film thickness measuring device 1 of this embodiment includes: a light source 10 that irradiates a sample 100 with light in a plane; an inclined dichroic mirror 22 that has a transmittance and reflectance corresponding to the wavelength in a specific wavelength band Change, the light from the sample 100 is separated by transmission and reflection; the area sensors 23, 24, etc., which capture the light separated by the inclined dichroic mirror 22; and the control device 30, which is based on The signals of the area sensors 23 and 24 that capture the light are used to estimate the film thickness of the sample 100; and the light source 10 irradiates light of the wavelength contained in the specific wavelength band of the inclined dichroic mirror 22.

In the film thickness measuring device 1 of the present embodiment, the sample 100 is irradiated with light of the wavelength contained in the specific wavelength band of the inclined dichroic mirror 22 in a planar manner. Furthermore, in the film thickness measuring apparatus 1 of this embodiment, the inclined dichroic mirror 22 transmits and reflects the light from the sample 100 and separates it. Here, the inclined dichroic mirror 22 is in a specific wavelength band, and the transmittance and reflectance change in accordance with the wavelength. Therefore, the transmitted ratio and the reflected ratio of the light separated in the inclined dichroic mirror 22 change in accordance with the wavelength. Moreover, by capturing the separated light in the area sensors 23 and 24, the ratio of the transmitted light and the ratio of the reflected light can be specified, and as a result, the wavelength can be specified. Furthermore, in the control device 30, the film thickness of the sample 100 can be estimated based on the signals from the area sensors 23 and 24. Since the film thickness can be estimated based on the information indicating the wavelength, the wavelength is estimated based on the imaging results of the area sensors 23 and 24 as described above, so by considering the signal containing the information of the wavelength (from the area sensor 23 , 24 signal), and the film thickness of the sample 100 can be estimated with high accuracy. Furthermore, in the film thickness measuring device 1 of this embodiment, the sample 100 is irradiated with light in a planar manner, and the film thickness in the surface of the sample 100 is estimated corresponding to the light from the sample 100. Compared with the case where a sensor or a line scan changes the light irradiation range while estimating the film thickness in the plane, the film thickness distribution in the plane can be estimated at a high speed. As described above, according to the film thickness measuring device 1 of this embodiment, the film thickness of the sample 100 can be measured at high speed.

Fig. 10 is a graph showing the result of comparison between the film thickness measuring device 1 of the present embodiment and the comparative example. As shown in FIG. 10, in the case where the film thickness is measured point by point by the point sensor, it takes about 4 hours of measurement time, for example. In addition, 4 hours here is the measurement time when, for example, about 16000 points are tested. Moreover, as shown in FIG. 10, in the case of measuring the film thickness line by line by line scanning, it takes about 3 minutes for the measurement time, for example. On the other hand, as shown in FIG. 10, in the film thickness measuring device 1 of the present embodiment, the sample 100 is irradiated with light in a plane, and the film thickness in the plane is measured in batches (simultaneously), so the measurement time is It becomes about 5 seconds. In this way, the film thickness measurement device 1 of the present embodiment can estimate the in-plane film thickness distribution at high speed compared with the point sensor or line scan of the comparative example. In addition, in the film thickness measuring device 1 of this embodiment, the error between the measurement result and the actual film thickness can be set to 0.1% or less. In this way, the film thickness measuring device 1 of the present embodiment can simultaneously reduce the measurement time related to the film thickness and improve the measurement accuracy. In addition, it is difficult to embed the point sensor and the line scan structure (installation to the device), but the film thickness measuring device 1 of the present embodiment is easy to embed.

In the above-mentioned film thickness measuring device 1, the control device 30 can estimate the film thickness corresponding to each pixel based on the wavelength information of each pixel of the area sensors 23 and 24. According to such a configuration, the film thickness distribution of the irradiation surface of the sample 100 can be estimated in more detail (for each pixel).

In the above-mentioned film thickness measuring device 1, the control device 30 can further consider the angle of the light irradiated on the sample 100 to estimate the film thickness. If the angle of the light irradiated on the sample 100 changes, the optical path changes. Therefore, there are cases where the film thickness cannot be estimated with high accuracy based on only the wavelength information. At this point, by further considering the angle of the light irradiated on the sample 100, the film thickness can be estimated with higher accuracy corresponding to the actual light path. Specifically, the film thickness is estimated using the above formula (8).

In the above-mentioned film thickness measuring device 1, the light source 10 can irradiate the sample 100 with diffused light. Thereby, the surface of the sample 100 can be irradiated with light uniformly.

In the above-mentioned film thickness measuring device 1, the light source 10 may have a light guide plate 10d that generates diffused light (refer to FIG. 2(a)). Thereby, a compact structure can be achieved, and the surface of the sample 100 can be uniformly irradiated with light.

The above-mentioned film thickness measuring device 1 may further include band-pass filters 25 and 26 arranged between the inclined dichroic mirror 22 and the area sensors 23 and 24. Thereby, light outside the desired wavelength range can be removed, and the accuracy of film thickness estimation can be improved.

The film thickness measurement method of this embodiment is implemented by the film thickness measurement device 1, and includes: a first step of irradiating the sample 100 with light in a plane; and a second step of imaging the sample 100 separated by an inclined dichroic mirror 22 The inclined dichroic mirror 22 carries a specific wavelength band, and the transmittance and reflectance change according to the wavelength, and the light from the sample 100 is separated by transmission and reflection; and the third step , Which derives the wavelength based on the imaging results, and estimates the film thickness of the sample 100 based on the wavelength. According to such a film thickness measurement method, the film thickness of the sample 100 can be measured at a high speed.

As mentioned above, although the embodiment of this invention was described, this invention is not limited to the said embodiment. The film thickness measuring device 1 can be applied to the film thickness measurement of various samples 100. As shown in FIG. 11, as the sample 100, consider the semiconductor element 100A, the flat panel display 100B, the film member 100C, the electronic component 100D, and other components 100E other than the electronic component.

That is, the film thickness measuring device 1 can measure the thickness of the film 101 formed on the substrate 102 as a wafer for the semiconductor element 100A. In this case, as the device configuration, a wafer transfer and holding mechanism including an arm, a cassette, a front-opening wafer transfer cassette, a conveyor, and a movable stage is used.

In addition, the film thickness measuring device 1 can measure the thickness of the film 101 formed on the substrate 102 made of glass, film, sheet, or the like for the flat panel display 100B. In this case, as the device configuration, a conveying and holding mechanism including an arm, a glass table, a conveyor, and a moving stage is used.

In addition, the film thickness measuring device 1 can measure the thickness of the film 101 formed on the substrate 102 made of glass, film, sheet, etc., for the film member 100C. In this case, as the device configuration, a conveying and holding mechanism including an arm, a glass table, a conveyor, and a moving stage is used. In addition, for the film member 100C, for example, as shown in FIG. 12, the film member 100C conveyed in one direction can be continuously imaged, and the imaging regions can be joined to each other to measure the film thickness of the entire film member 100C that is conveyed.

In addition, the film thickness measuring device 1 can measure the thickness of the film 101 formed on the substrate 102 as the substrate for the electronic component 100D. In this case, as the device configuration, a wafer transport and holding mechanism including an arm, a cassette, a front-opening wafer transfer cassette, a conveyor, a sample stage, and a movable stage is used.

In addition, the film thickness measuring device 1 can measure the thickness of the film 101 formed on the substrate 102 as the substrate for the component 100E. The film of the part 100E is, for example, a film of a molded product, and the film thickness measurement in this case is, for example, the measurement of the thickness of the film coating. As the device configuration, a wafer transport and holding mechanism including an arm, a cassette, a front-opening wafer transfer box, a conveyor, a sample stage, and a movable stage is used.

In addition, the relative film thickness distribution is derived by the above-mentioned film thickness measurement. In addition, by detecting the spectral information (reference spectral information) of a certain point of the sample 100, the relative film thickness distribution and the reference spectral information can be determined. Derive the ultimate absolute value of the film thickness of each area respectively. FIG. 13 is a diagram schematically showing a film thickness measuring device 1A of a modified example. The film thickness measurement device 1A also includes a half mirror 29 and a spectroscope 50 in addition to the respective configurations of the film thickness measurement device 1 described in the embodiment. The half mirror 29 reflects light at a point near the center of the sample 100, for example. The spectroscope 50 obtains the spectroscopic spectral data of the light at that point, that is, the reference spectral information. In this way, by obtaining the reference spectrum information and determining the value of m in equations (7) and (8), not only the relative change in film thickness can be derived, but also the absolute value of the film thickness in each region can be derived. In addition, the method of measuring the absolute value of the film thickness is not limited to the above.

1,1A: Film thickness measuring device 2nd, 2ndcosθ: optical path difference 10: Light source (light irradiation part) 10A: Flat dome type light source 10B: Dome-shaped light source/light source 10c, 10e: LED 10d: light guide plate 10f: round top 20: Camera system 21: lens 22: Tilted dichroic mirror 23, 24: Area sensor (camera department) 25, 26: Band pass filter 29: Half mirror 30: control device (analysis department) 50: splitter 100: Sample (object) 100A: Semiconductor components 100B: Flat panel display 100C: Membrane member 100D: Electronic parts 100E: Parts 101: Membrane 102: Substrate m: positive integer R: The amount of reflected light T: The amount of transmitted light X1: Waveform X4: Characteristics of tilted dichroic mirror X10: wavelength band X20: light λ0: The center wavelength of the tilted dichroic mirror λ1,λ2: wavelength θ: incident angle

Fig. 1 is a diagram schematically showing a film thickness measuring device according to an embodiment of the present invention. Fig. 2 is a diagram schematically showing an example of a light source, Fig. 2(a) shows a flat dome lighting, and Fig. 2(b) shows a dome lighting. Figure 3 is a diagram illustrating the relationship between the characteristics of the dichroic mirror and the wavelength of the light emitted from the light source. Figure 4 is a diagram illustrating the spectrum of light and the characteristics of the tilted dichroic mirror. Fig. 5 is a diagram illustrating the wavelength shift corresponding to the amount of transmitted light and the amount of reflected light. Figure 6 is a graph showing the relationship between wavelength and film thickness. Figure 7 is a diagram illustrating the principle of film thickness measurement. Fig. 8 is a diagram illustrating the difference in the incident angle of light to the camera system. Figure 9 (a) and (b) are diagrams illustrating the correction of the measured film thickness. Fig. 10 is a graph showing the result of comparison between the film thickness measuring device of the present embodiment and the comparative example. Fig. 11 is a diagram illustrating a film thickness measuring device of a modified example. Fig. 12 is a diagram illustrating a film thickness measuring device of a modified example. Fig. 13 is a diagram schematically showing a film thickness measuring device of a modified example.

1: Film thickness measuring device

10: Light source (light irradiation part)

20: Camera system

21: lens

22: Tilted dichroic mirror

23, 24: Area sensor (camera department)

25, 26: Band pass filter

30: control device (analysis department)

100: Sample (object)

Claims (7)

A film thickness measuring device, which is provided with: The light irradiating part irradiates the object with light in a planar manner; An optical element, in which the transmittance and reflectance in a specific wavelength band change corresponding to the wavelength, and the light from the aforementioned object is separated by transmitting and reflecting; The imaging part, which captures the light separated by the aforementioned optical element; An analysis unit that estimates the film thickness of the object based on the signal from the imaging unit that captured the light; and The light irradiating part irradiates light of a wavelength included in the specific wavelength band of the optical element. The film thickness measurement device of claim 1, wherein the analysis unit estimates the film thickness corresponding to each pixel based on the wavelength information of each pixel of the imaging unit. The film thickness measuring device of claim 1 or 2, wherein the analysis unit further considers the angle of light irradiated on the object to estimate the film thickness. The film thickness measuring device according to any one of claims 1 to 3, wherein the light irradiating section irradiates the object with diffuse light. The film thickness measuring device of claim 4, wherein the light irradiation section has a light guide plate that generates the diffused light. The film thickness measuring device according to claim 1, further comprising a band pass filter arranged between the optical element and the imaging unit. A method for measuring film thickness, which comprises: The first step is to irradiate the object with light in a planar manner; The second step is to photograph the light separated by the optical element. The optical element has a transmittance and reflectance corresponding to the wavelength change in a specific wavelength band, and the light from the aforementioned object is separated by transmission and reflection; and In the third step, the wavelength is derived based on the imaging result, and the film thickness of the object is estimated based on the wavelength.

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